Genomic structure of an attenuated quasi species of HIV-1 from a blood transfusion donor and recipients.

A blood donor infected with human immunodeficiency virus-type 1 (HIV-1) and a cohort of six blood or blood product recipients infected from this donor remain free of HIV-1-related disease with stable and normal CD4 lymphocyte counts 10 to 14 years after infection. HIV-1 sequences from either virus isolates or patient peripheral blood mononuclear cells had similar deletions in the nef gene and in the region of overlap of nef and the U3 region of the long terminal repeat (LTR). Full-length sequencing of one isolate genome and amplification of selected HIV-1 genome regions from other cohort members revealed no other abnormalities of obvious functional significance. These data show that survival after HIV infection can be determined by the HIV genome and support the importance of nef or the U3 region of the LTR in determining the pathogenicity of HIV-1.

Climatic models to predict occurrence of Fusarium toxins in wheat and maize.

Although forecasting Fusarium infections have useful implications, it may be argued that forecasting Fusarium toxins is more useful to help reduce their entry into the food chain. Several disease incidence models have been commercialized for wheat, but only one toxin prediction model from Ontario, Canada, "DONcast", has been validated extensively and commercialized to date for wheat, and another has been proposed for maize. In the development of these predictive tools, the variation in toxin levels associated with year and agronomic effects was estimated from simple linear models using wheat and maize samples taken from farm fields. In wheat, environment effects accounted for 48% of the variation in deoxynivalenol (DON) across all fields, followed by variety (27%), and previous crop (14 to 28%). In maize, hybrid accounted for 25% of the variation of either DON or fumonisin, followed by environment (12%), and when combined 42% of the variability was accounted for. The robust site-specific, DON forecast model accounted for up to 80% of the variation in DON, and has been used commercially for 5 years in Canada. Forecasting DON and fumonisins in maize is more difficult, because of its greater exposure to infection, the role of wounding in infection, the more important role of hybrid susceptibility, and the vast array of uncharacterized hybrids available in the marketplace. Nevertheless, using data collected from controlled experiments conducted in Argentina and the Philippines, a model was developed to predict fumonisin concentration using insect damage and weather variables, accounting for 82% of the variability of fumonisins. Using mycotoxins as a measure of disease outcome, as opposed to disease symptoms, offers a more robust prediction of mycotoxin risk, and it accounts for mycotoxin accumulation that occurs frequently in the absence of any change in Fusarium symptoms.

Syncytium-inducing phenotype and zidovudine susceptibility of HIV-1 isolated from post-mortem tissue.

OBJECTIVE: To establish the syncytium-inducing (SI) phenotype and zidovudine (ZDV) susceptibility of HIV-1 isolates obtained from autopsy specimens. METHODS: Isolation of HIV was attempted from autopsy specimens obtained from 76 AIDS patients. Specimens of lymph node, spleen, spinal cord, brain and cerebrospinal fluid (CSF) were processed and cultured with peripheral blood mononuclear cells (PBMC) from seronegative donors. Biological phenotype was determined in a T-lymphocyte line (MT-2). ZDV susceptibility was evaluated in a PBMC-based assay. Sequencing of amino-acid codons in the reverse transcriptase gene previously shown to be associated with ZDV resistance was carried out on a subgroup of isolates. RESULTS: HIV was recovered from tissue specimens and CSF up to 5 days post-mortem, but recovery rate of infectious virus decreased as the time between autopsy and specimen processing increased. There was a lack of concordance between PBMC isolates and isolates from different tissue sites with respect to SI phenotype. ZDV-resistant virus was isolated from post-mortem specimens of patients who had received long-term ZDV therapy up until or shortly before their death. ZDV-sensitive virus re-emerged in the lymph node of patients who ceased treatment several months prior to death. Phenotypically sensitive virus obtained from lymph node tissue of three patients after a relatively short time off ZDV (4-6 months) retained some of the amino-acid substitutions known to be associated with resistance. CONCLUSION: The data suggests that ZDV resistance and re-emergence of sensitive virus does not originate in peripheral cells, and that these cells and tissues are seeded with virus present elsewhere, possibly in the germinal centres of the lymph node.

Applications of a simultaneous atomic emission mass spectral gas chromatography detector in drug analysis.

For gas chromatographic eluents a microwave induced plasma (MIP) emission detector has two important features for a wide range of nonmetals. These features are (1) elemental selectivity and (2) the ability to determine elemental composition. These capabilities, used individually or in combination, can provide important information which is largely complementary to mass spectral data. Simultaneous determination of the MIP emission and mass spectral data for individual chromatographic peaks can be very useful in resolving a variety of problems encountered in pharmaceutical analysis. Several of these possible applications are illustrated with specific examples.

Comparison of three treatment procedures for minimizing ankle sprain swelling.

The purpose of this study was to compare the effects of cold, heat, and contrast bath treatments on the amount of edema in first- and second-degree sprained ankles during the postacute phase of rehabilitation. Thirty subjects with postacute sprained ankles were assigned to a cold (n = 10), heat (n = 10), or contrast bath (n = 10) treatment group. A specially constructed tank was used to take pretreatment and posttreatment volumetric measurements of subjects' sprained ankles. Descriptive statistics, a 3 x 3 two-way analysis of variance for repeated measures, and Tukey's Honestly Significant Difference post hoc test revealed that cold therapy produced the least edema in subjects with sprained ankles (p less than .05). All three treatments (cold, heat, and contrast bath) produced an increase in the amount of edema in the postacute sprained ankles of the subjects. Heat and contrast bath therapy produced almost identical increases in the amount of ankle edema on each of the three days of the study. We concluded that cold therapy is the most appropriate of the three treatments if the therapeutic objective is to minimize edema before rehabilitative exercise during the third, fourth, and fifth days postinjury for first- and second-degree ankle sprains.

Fentanyl-induced chest wall rigidity in a neonate: a case report.

Fentanyl-induced chest wall rigidity occurred in an 8-week-old infant girl recovering from surgical repair of coarctation of the aorta. The neonate received 30 minutes of a moderate dose continuous infusion of fentanyl before chest wall rigidity developed. Association of the chest wall rigidity with the fentanyl infusion resulted in the appropriate intervention of narcotic reversal and prevented irreversible hypoxic sequelae. Patients receiving fentanyl, even at moderate doses, are at risk for the development of chest wall rigidity.

Using Weather Variables Pre- and Post-heading to Predict Deoxynivalenol Content in Winter Wheat.

Substantial economic losses have occurred because of unacceptable concentrations of deoxynivalenol (DON) in wheat. Accurate predictions of DON in mature grain at wheat heading are needed to make decisions on whether a control strategy is needed. Our objective was to identify important weather variables, and their timing, for predicting concentrations of DON in mature grain at wheat heading. We measured the concentration of DON in 399 farm fields in southern Ontario, Canada, from 1996 to 2000. DON varied in field samples from undetectable to over 29 µg g-1. Weather variables, such as daily rainfall, daily minimum and maximum air temperatures, and hourly relative humidity, were estimated for each field from nearby weather stations and were normalized to the date of 50% head emergence. Stepwise multiple regression procedures determined the most important weather variables and their timing around heading. DON was responsive to weather in three critical periods around heading. In the first period, 4 to 7 days before heading, DON generally increased with the number of days with >5 mm of rain and decreased with the number of days of <10°C. In the second period, 3 to 6 days after heading, DON increased with the number of days of rain >3 mm and decreased with days exceeding 32°C. In the third period, 7 to 10 days after heading, DON increased with number of days with >3 mm of rain. A relationship between relative humidity and DON was not detected. Overall, 73% of the variation in the concentration of DON was explained by using weather from all three critical periods. Concentrations of DON <2.0 µg g-1 were predicted best; in fact, concentrations of DON of <1.0 µg g-1 were predicted correctly on over 89% of the fields used to train the model.

Effect of Bt-Corn Hybrids on Deoxynivalenol Content in Grain at Harvest.

Concentrations of the mycotoxins deoxynivalenol (DON) and fumonisin B1 in grain were compared among Bt-transformed corn hybrids and their non-Bt isolines on 102 commercial corn fields across Ontario from 1996 to 1999. Intensities of naturally occurring populations of Ostrinia nubilalis were assessed from tunneling measurements in the stalks of non-Bt isolines in 1996 and 1997. Mean concentrations of fumonisin B1 across hybrids were <0.25 µg g-1 in every year of the study. Relationships between the concentration of fumonisin B1 and intensity of O. nubilalis or with the use of Bt corn hybrids could not be determined because the concentrations of fumonisin B1 were below the lower limit of detection in most fields (<0.1 µg g-1). However, DON was more prevalent with mean concentrations across fields from 0.42 µg g-1 in 1997 to 1.12 µg g-1 in 1999. The effect of Bt hybrids on reducing concentrations of DON was mainly dependent on the intensity of O. nubilalis in each field. Where a high intensity (stalk injury) of O. nubilalis was observed (>4 cm of tunnel per stalk in the non-Bt), the use of Bt hybrids reduced concentrations of DON by an average of 59% from concentrations in the non-Bt isoline. Where the intensity of O. nubilalis was low (<4 cm of tunneling per stalk), concentrations of DON were not different among Bt and non-Bt hybrids. Concentrations of DON were low and not different between events Bt11 and 176 among Bt hybrids. A quadratic relationship was developed showing that the concentration of DON increased with intensity of O. nubilalis feeding. This study cautiously supports the use of Bt corn to reduce the risk of high concentrations of DON at harvest in Ontario.

The effects of intermittent compression on edema in postacute ankle sprains.

The purpose of this study was to compare the effects of three treatment protocols on pitting edema in patients with first- and second-degree sprained ankles. Thirty subjects with postacute (greater than 24 hours postinjury) ankle sprains and pitting edema but not requiring cast immobilization were randomly assigned to an elastic wrap group (N = 10), an intermittent compression group (N = 10), or an elevated control group (N = 10). Pretreatment and posttreatment volumetric measurements of the subjects' ankles were obtained by the water displacement method. After the pretreatment measurement, the groups were treated for 30 minutes. All subjects' ankles were elevated by raising the foot section of an adjustable table to a 45 degrees angle during treatment. For the first treatment group, the intermittent compression device was set at 40-50 mm Hg, with a 60-second on time and a 15-second off time. For the second treatment group, an elastic wrap was applied from the heads of the metatarsals to 12.7 centimeters above the malleoli. Control group subjects received only the elevated position as their treatment. A three by two repeated measures ANOVA with a follow-up post hoc test revealed that the elevated control group subjects had the least amount of edema (p < .0006). The two compression protocols produced increased edema in the subjects' sprained ankles following treatment. In conclusion, elevation is the most appropriate of the three treatment protocols if the major therapeutic objective is to minimize edema in the postacute phase of rehabilitation. J Orthop Sports Phys Ther 1991;14(2):65-69.

Comparison of the Effects of the Anderson Knee Stabler and McDavid Knee Guard on the Kinematics of the Lower Extremity during Gait*.

* This study was completed in partial fulfillment of Ms. Van Horn's master's degree, University of North Carolina at Chapel Hill. The purpose of this study was to compare gait patterns among subjects wearing Anderson Knee Stabler braces, McDavid Knee Guards, and no braces. Fifteen male subjects were filmed while running on a treadmill at 4 mph and 8 mph without a brace, with an Anderson Knee Stabler, and with a McDavid Knee Guard. Fourteen gait variables were measured for each brace and speed condition. Analysis of the variables with multivariate ANOVA indicated that there was an increase in hip and knee flexion and knee angular velocity with and without braces at 8 mph as compared to 4 mph, a decrease in knee extension when either brace was worn, and minimal gait pattern differences with the Anderson Knee Stabler as compared with the McDavid Knee Guard (all results p < 0.05). The results of this study demonstrate that no clear superiority exists between the braces' effect on the gait characteristics measured. Therefore, other parameters should be considered when making brace selections.J Orthop Sports Phys Ther 1988;9(7):254-260.

Surgical instrument restraint in weightlessness.

BACKGROUND: Performing a surgical procedure during spaceflight will become more likely in the future as the duration of missions becomes longer. Only minimal surgical capability was available on previous missions since the definitive medical care time was short and the likelihood of a surgical event too low to justify carrying surgical hardware onboard. Early demonstrations of surgical procedures in the microgravity environment of parabolic flight indicated the need for careful logistical planning and restraint of surgical hardware. Human ergonomics also has more effect in microgravity than in the conventional 1-G environment. METHODS: Three methods of surgical instrument restraint--a Minor Surgical Kit (MSK), a Surgical Restraint Scrub Suit (SRSS), and a Surgical Tray (ST)--were evaluated in parabolic flight surgical procedures. RESULTS: The MSK was easily stored, easily deployed, and demonstrated the best ability to facilitate a surgical procedure in microgravity. CONCLUSION: Important factors in a surgical restraint system for microgravity include excellent organization of supplies, ability to maintain sterility, accessibility while providing secure restraint, ability to dispose of sharp items and biological trash, and ergonomic efficiency.

Isokinetic strength following knee arthroscopy.

This study objectively evaluates recovery of quadriceps and hamstring strength following knee arthroscopy in a group of 43 patients given rehabilitation instructions, but limited supervised rehabilitation. Although the patients did not complain of weakness or functional limitation, isokinetic testing 1, 3, and 8 weeks following surgery revealed persistent weakness in many patients. Incomplete recovery was most apparent when patients were categorized by the degree to which they had recovered normal strength. Results expressed as a mean for the entire group indicated reasonably good recovery and obscured the significant weakness persisting in some patients. Knee extension strength tested at 60 degrees/sec had returned to normal 8 weeks after arthroscopy in only 32% of the subjects. Hamstring strength recovery was better, with 71% having normal strength. Patients may not recognize or report muscular weakness following arthroscopy, yet following 8 weeks of self-supervised rehabilitation many will have objective evidence of persistent weakness. In asymptomatic patients the clinical significance of this weakness is unknown.

Hepatitis C seropositivity is not a risk factor for sensory neuropathy among patients with HIV.

BACKGROUND: Sensory neuropathy (SN) is common in patients with HIV. Hepatitis C (HCV) coinfection is often cited as an HIV-SN risk factor, but data to support this are lacking. This collaboration aimed to examine the association between HCV serostatus and SN risk among ambulatory HIV-positive patients. METHODS: Patients with HIV were assessed in cross-sectional studies in Baltimore, Jakarta, Johannesburg, Kuala Lumpur, Melbourne, and Sydney for SN (defined by both supportive symptoms and signs). HCV seropositivity was assessed as an SN risk using a chi(2) test, followed by logistic regression modeling to correct for treatment exposures and demographics. RESULTS: A total of 837 patients of African, Asian, and Caucasian descent were studied. HCV seroprevalence varied by site (Baltimore n = 104, 61% HCV+; Jakarta 96, 51%; Johannesburg 300, 1%; Kuala Lumpur 97, 10%; Melbourne 206, 16%; Sydney 34, 18%). HCV seropositivity was not associated with increased SN risk at any site, but was associated with reduced SN risk in Melbourne (p = 0.003). On multivariate analyses, the independent associations with SN were increasing age, height, and stavudine exposure. HCV seropositivity was not independently associated with an increased SN risk at any site, but associated independently with reduced SN risk in Baltimore (p = 0.04) and Melbourne (p = 0.06). CONCLUSIONS: Hepatitis C (HCV) seropositivity was not associated with increased sensory neuropathy risk among HIV-positive patients at any site. While we were unable to assess HCV RNA or liver damage, the data suggest that HCV coinfection is not a major contributor to HIV-SN. HCV = hepatitis C; SN = sensory neuropathy.

Alternatively spliced RNAs encode several isoforms of CD46 (MCP), a regulator of complement activation.

Five alternative cDNA clones were isolated for CD46, also known as the membrane cofactor protein (MCP) for the factor I-mediated cleavage of the complement convertases. One of these cDNA clones (a) was identical to an earlier MCP clone. The other four CD46 clones contained the four NH2-terminal short consensus repeat (SCR) units of MCP, but differed at the region encoding the carboxyl-terminal of the protein which includes an extracellular segment rich in Ser, Thr, and Pro residues, a hydrophobic membrane-spanning domain, and a 33 amino acid cytoplasmic tail. The different CD46 cDNAs have variously: (b) inserted a 93 base pair (bp) exon resulting in a new cytoplasmic tail of 26 amino acids; (c) deleted a 42 bp exon from the extracellular Ser/Thr rich region: (d) used a cryptic splice acceptor sequence to delete 37 bp from an exon encoding transmembrane sequence; or (e) failed to splice the intron after the four SCR units. These were shown by northern blot and polymerase chain reaction to arise by alternative splicing of CD46 RNA. Forms (a), (b), and (c) of CD46 RNA are common in placental RNA, but (d) was rare, and (e) was incompletely processed and therefore aberrant. The polymerase chain reaction (PCR) was used to map the sites of the intron/exon junctions and demonstrate further possible splice variants of CD46. The alternative RNAs for CD46 may correlate to the different isoforms of CD46 found in different tissues, tumors, and in serum.

Reverse transcriptase mutations in sequential HIV-1 isolates in a patient with AIDS.

Sequential human immunodeficiency virus type 1 (HIV-1) isolates were obtained over a 29-month period from a person before, during, and after AZT therapy. DNA sequence analysis of polymerase chain-amplified reverse-transcriptase gene showed a gradual accumulation of mutations to peak resistance (IC50 2.13 microM AZT) in association with mutations at codons 44, 210, and 369, as well as at 41, 67, 70, and 215. Eight months after cessation of AZT therapy, when an HIV-1 isolate from the patient was again sensitive to AZT, these mutations had all returned to the pretherapy sequence.

Characterisation of foscarnet-resistant strains of human immunodeficiency virus type 1.

Foscarnet is a broad-spectrum viral DNA polymerase inhibitor active in vitro and in vivo against human immunodeficiency virus type 1 (HIV-1). Strains of HIV-1 resistant to foscarnet were selected by in vitro passage in increasing concentrations of drug. Reduced susceptibility to foscarnet was evident at the levels of both HIV-1 replication and reverse transcriptase. Biologically cloned, foscarnet-resistant strains with distinct genotypes were hypersensitive to zidovudine, azidodeoxyuridine, nevirapine, and R82913 but had unchanged susceptibility to zalcitibine and didanosine. The reverse transcriptase of foscarnet-resistant strains had unique substitutions Glu89-Lys, Leu92-Ile, or Ser156-Ala, the third being associated with six polymorphic changes. Introduction of these mutations into wild-type HIV-1 by site-directed mutagenesis confirmed their role in foscarnet resistance. In the three-dimensional structure of the reverse transcriptase enzyme these amino acids are located close to the template strand of the template primer and far away from the putative pyrophosphate binding site, suggesting that the mechanism by which HIV-1 becomes resistant to foscarnet is indirect. Foscarnet resistance is thus likely to be mediated through an altered interaction of the mutant enzyme with the template strand of the template primer which distorts the geometry of the polymerase active site and thereby decreases foscarnet binding.

An in vivo mutation from leucine to tryptophan at position 210 in human immunodeficiency virus type 1 reverse transcriptase contributes to high-level resistance to 3'-azido-3'-deoxythymidine.

Sequencing of the reverse transcriptase (RT) region of 26 human immunodeficiency virus type 1 (HIV-1) isolates from eight patients treated with 3'-azido-3'-deoxythymidine (AZT) revealed a mutation at codon 210 from TTG (leucine) to TGG (tryptophan) exclusively in association with resistance to AZT. The mutation Trp-210 was observed in 15 of the 20 isolates phenotypically resistant to AZT, being more commonly observed than resistance-associated mutations at codons 67, 70, and 219. Trp-210 was never observed before the emergence of resistance-associated mutations Leu-41 and Tyr-215, and in a sequential series of five isolates from one patient the order of emergence of mutations was found to be Tyr-215, Leu-41, and then Trp-210. Trp-210 was also found in association with the Leu-41, Asn-67, Arg-70, and Tyr-215 resistance genotype. To define the role of Trp-210 in AZT resistance, molecular HIV-1 clones were constructed with various combinations of RT mutations at codons 41, 67, 70, 210, and 215 and tested for susceptibility to AZT. In clones with polymerase genes derived either from HXB2-D or clinical isolates, Trp-210 alone did not increase AZT resistance, whereas in conjunction with Leu-41 and Tyr-215, Trp-210 contributed to high-level resistance (50% inhibitory concentration of >1 microM). In HXB2-D, Trp-210 with Tyr-215 generated a virus with resistance comparable to one with Leu-41, Tyr-215, and Trp-210. Inserting Trp-210 into the genetic context of mutations at codons 41, 67, 70, and 215 further enhanced resistance from a 50% inhibitory concentration of 1.44 microM to 8.41 microM. Molecular modeling of the tertiary structure of HIV-1 RT revealed that the distance between the side chains of Trp-210 (in helix alphaF) and Tyr-215 (in strand beta11a) approximated 4 A (1 A = 0.1 nm), sufficiently close to result in significant energetic interaction between these two aromatic side chains. In conclusion, Trp-210 contributes significantly to phenotypic AZT resistance of HIV-1 by augmenting resistance at least three- to sixfold in the context of two resistant genotypes, and its effect may require an interaction with an aromatic amino acid at position 215.